Run ESLint and Prettier linting in worker threads

.changeset/few-rules-marry.md

@@ -0,0 +1,7 @@
+---
+"skuba": minor
+---
+
+lint: Run ESLint and Prettier in worker threads
+
+This reduces the number of Node.js processes spawned by `skuba lint`. We've also been able to significantly enhance our logging output as a result, particularly when the `--debug` flag is supplied.

.gitignore

@@ -19,4 +19,5 @@ yarn-error.log
 # end managed by skuba
 
 /integration/format/
+/integration/lint/
 /template/**/yarn.lock

docs/cli/lint.md

@@ -47,11 +47,9 @@ This command should be run in CI to verify that [`skuba format`] was applied and
 ```shell
 skuba lint
 
-# Prettier | Checking formatting...
-# Prettier | All matched files use Prettier code style!
-# Prettier | prettier --check . exited with code 0
-# ESLint   | eslint --ext=js,ts,tsx --report-unused-disable-directives . exited with code 0
-# tsc      | TSFILE: ...
+# ESLint   | Processed 123 files in 1.23s.
+# Prettier | Processed 123 files in 1.23s.
+# tsc      | TSFILE: /lib/tsconfig.tsbuildinfo
 # tsc      | tsc --noEmit exited with code 0
 ```
 

src/cli/__snapshots__/format.int.test.ts.snap

@@ -130,6 +130,7 @@ Formatted 1 file:
 a/a/a.ts
 
 ESLint found issues that require triage.
+
 "
 `;
 

src/cli/__snapshots__/lint.int.test.ts.snap

@@ -0,0 +1,122 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`fixable 1`] = `
+"
+ESLint   | Processed 2 files in <random>s.
+ESLint   | 
+<random>/a/a/a.ts
+  3:1  error  \`fs\` import should occur before import of \`path\`  import/order
+
+✖ 1 problem (1 error, 0 warnings)
+  1 error and 0 warnings potentially fixable with the \`--fix\` option.
+
+Prettier | Processed 6 files in <random>s.
+Prettier | Flagged 3 files:
+Prettier | b.md
+Prettier | c.json
+Prettier | d.js
+tsc      | TSFILE: <random>/lib/tsconfig.tsbuildinfo
+tsc      | tsc --noEmit exited with code 0
+
+ESLint, Prettier found issues that require triage.
+
+"
+`;
+
+exports[`ok --debug 1`] = `
+"
+ESLint   | Initialising ESLint...
+ESLint   | Processing files...
+ESLint   | Processed 2 files in <random>s.
+ESLint   | ○ a/a/a.ts
+ESLint   | ○ d.js
+Prettier | Initialising Prettier...
+Prettier | Detected project root: <random>
+Prettier | Discovering files...
+Prettier | Discovered 6 files.
+Prettier | Reading files...
+Prettier | Linting files...
+Prettier | b.md
+Prettier |   parser: markdown
+Prettier | c.json
+Prettier |   parser: json
+Prettier | d.js
+Prettier |   parser: babel
+Prettier | package.json
+Prettier |   parser: json-stringify
+Prettier | tsconfig.json
+Prettier |   parser: json
+Prettier | a/a/a.ts
+Prettier |   parser: typescript
+Prettier | Writing 0 files...
+Prettier | Processed 6 files in <random>s.
+tsc      | TSFILE: <random>/lib/tsconfig.tsbuildinfo
+tsc      | Files: <random>
+tsc      | Lines of Library: <random>
+tsc      | Lines of Definitions: <random>
+tsc      | Lines of TypeScript: <random>
+tsc      | Lines of JavaScript: <random>
+tsc      | Lines of JSON: <random>
+tsc      | Lines of Other: <random>
+tsc      | Nodes of Library: <random>
+tsc      | Nodes of Definitions: <random>
+tsc      | Nodes of TypeScript: <random>
+tsc      | Nodes of JavaScript: <random>
+tsc      | Nodes of JSON: <random>
+tsc      | Nodes of Other: <random>
+tsc      | Identifiers: <random>
+tsc      | Symbols: <random>
+tsc      | Types: <random>
+tsc      | Instantiations: <random>
+tsc      | Memory used: <random>K
+tsc      | Assignability cache size: <random>
+tsc      | Identity cache size: <random>
+tsc      | Subtype cache size: <random>
+tsc      | Strict subtype cache size: <random>
+tsc      | I/O Read time: <random>s
+tsc      | Parse time: <random>s
+tsc      | ResolveModule time: <random>s
+tsc      | ResolveTypeReference time: <random>s
+tsc      | Program time: <random>s
+tsc      | Bind time: <random>s
+tsc      | Check time: <random>s
+tsc      | I/O Write time: <random>s
+tsc      | printTime time: <random>s
+tsc      | Emit time: <random>s
+tsc      | Total time: <random>s
+tsc      | tsc --extendedDiagnostics --noEmit exited with code 0
+
+"
+`;
+
+exports[`ok 1`] = `
+"
+ESLint   | Processed 2 files in <random>s.
+Prettier | Processed 6 files in <random>s.
+tsc      | TSFILE: <random>/lib/tsconfig.tsbuildinfo
+tsc      | tsc --noEmit exited with code 0
+
+"
+`;
+
+exports[`unfixable 1`] = `
+"
+ESLint   | Processed 2 files in <random>s.
+ESLint   | 
+<random>/a/a/a.ts
+  3:1  error  \`fs\` import should occur before import of \`path\`  import/order
+  8:3  error  Unexpected console statement                      no-console
+
+✖ 2 problems (2 errors, 0 warnings)
+  1 error and 0 warnings potentially fixable with the \`--fix\` option.
+
+Prettier | Processed 6 files in <random>s.
+Prettier | Flagged 1 file:
+Prettier | a/a/a.ts
+tsc      | TSFILE: <random>/lib/tsconfig.tsbuildinfo
+tsc      | tsc --noEmit exited with code 0
+
+ESLint, Prettier found issues that require triage.
+
+"
+`;

src/cli/format.ts

@@ -33,6 +33,7 @@ export const format = async (args = process.argv) => {
   ];
 
   log.err(tools.join(', '), 'found issues that require triage.');
+  log.newline();
 
   process.exitCode = 1;
 };

src/cli/lint.int.test.ts

@@ -0,0 +1,108 @@
+import crypto from 'crypto';
+import fs from 'fs';
+import path from 'path';
+import stream from 'stream';
+
+import { copy } from 'fs-extra';
+
+import { lint } from './lint';
+
+jest.setTimeout(30_000);
+
+const stdoutMock = jest.fn();
+
+jest
+  .spyOn(console, 'log')
+  .mockImplementation((...args) => stdoutMock(`${args.join(' ')}\n`));
+
+const tscOutputStream = new stream.PassThrough().on('data', stdoutMock);
+
+const BASE_PATH = path.join(__dirname, '..', '..', 'integration', 'base');
+
+const TEMP_PATH = path.join(__dirname, '..', '..', 'integration', 'lint');
+
+const stdout = (randomMatcher: RegExp) =>
+  stdoutMock.mock.calls
+    .flat(1)
+    .join('')
+    .replace(/ in [\d\.]+s\./g, ' in <random>s.')
+    .replace(
+      /tsc      \| Lines of ([^:]+):[ ]+\d+/g,
+      'tsc      | Lines of $1: <random>',
+    )
+    .replace(
+      /tsc      \| Nodes of ([^:]+):[ ]+\d+/g,
+      'tsc      | Nodes of $1: <random>',
+    )
+    .replace(
+      /tsc      \| (Files|Identifiers|Symbols|Types|Instantiations|Memory used):[ ]+\d+/g,
+      'tsc      | $1: <random>',
+    )
+    .replace(
+      /tsc      \| (.+) cache size:[ ]+\d+/g,
+      'tsc      | $1 cache size: <random>',
+    )
+    .replace(
+      /tsc      \| (.+) time:[ ]+[\d\.]+s/g,
+      'tsc      | $1 time: <random>s',
+    )
+    .replace(randomMatcher, '<random>');
+
+const prepareTempDirectory = async (baseDir: string, tempDir: string) => {
+  await copy(baseDir, tempDir, { recursive: true });
+
+  process.chdir(tempDir);
+};
+
+const originalCwd = process.cwd();
+
+beforeEach(() => {
+  jest.clearAllMocks();
+
+  process.exitCode = undefined;
+});
+
+afterAll(() => {
+  // Restore the original working directory to avoid confusion in other tests.
+  process.chdir(originalCwd);
+
+  // Clean up temporary directories to avoid subsequent formatting and linting
+  // warnings and to save on disk space. This can be commented out to inspect
+  // the output.
+  return fs.promises.rm(TEMP_PATH, {
+    force: true,
+    recursive: true,
+  });
+});
+
+interface Args {
+  args: string[];
+  base: string;
+  exitCode: number | undefined;
+}
+
+test.each`
+  description     | args           | base           | exitCode
+  ${'fixable'}    | ${[]}          | ${'fixable'}   | ${1}
+  ${'ok'}         | ${[]}          | ${'ok'}        | ${undefined}
+  ${'ok --debug'} | ${['--debug']} | ${'ok'}        | ${undefined}
+  ${'unfixable'}  | ${[]}          | ${'unfixable'} | ${1}
+`('$description', async ({ args, base, exitCode }: Args) => {
+  const baseDir = path.join(BASE_PATH, base);
+
+  const tempDir = path.join(
+    TEMP_PATH,
+    `${base}-${crypto.randomBytes(32).toString('hex')}`,
+  );
+
+  await prepareTempDirectory(baseDir, tempDir);
+
+  await expect(
+    // Force `--serial` as worker threads can't run in a TypeScript context.
+    lint([...args, '--serial'], tscOutputStream),
+  ).resolves.toBeUndefined();
+
+  expect(stdout(new RegExp(tempDir, 'g'))).toMatchSnapshot();
+
+  expect(process.exitCode).toBe(exitCode);
+});

src/cli/lint.test.ts

@@ -1,95 +1,7 @@
 // Uncomment the following line when there's an intentionally skipped test.
 // /* eslint-disable jest/no-disabled-tests */
 
-import concurrently from 'concurrently';
-
-import { internalLint, lint } from './lint';
-
-jest.mock('concurrently');
-
-const concurrentlyCalls = () =>
-  (concurrently as unknown as jest.Mock<typeof concurrently>).mock.calls
-    .flat(2)
-    .map(({ env, maxProcesses, ...rest }) => ({
-      ...(env !== undefined && { env: 'REDACTED' }),
-      ...(maxProcesses !== undefined && { maxProcesses: 'REDACTED' }),
-      ...rest,
-    }));
-
-describe('lint', () => {
-  afterEach(jest.clearAllMocks);
-
-  it('handles no flags', async () => {
-    await expect(lint([])).resolves.toBeUndefined();
-
-    expect(concurrentlyCalls()).toMatchInlineSnapshot(`
-      Array [
-        Object {
-          "command": "eslint --ext=js,ts,tsx --report-unused-disable-directives .",
-          "env": "REDACTED",
-          "name": "ESLint  ",
-          "prefixColor": "magenta",
-        },
-        Object {
-          "command": "tsc --noEmit",
-          "env": "REDACTED",
-          "name": "tsc     ",
-          "prefixColor": "blue",
-        },
-        Object {
-          "command": "prettier --check .",
-          "env": "REDACTED",
-          "name": "Prettier",
-          "prefixColor": "cyan",
-        },
-        Object {
-          "maxProcesses": "REDACTED",
-          "outputStream": undefined,
-          "prefix": "{name} |",
-        },
-      ]
-    `);
-  });
-
-  it('handles debug flag', async () => {
-    await expect(
-      lint(['something', '--DeBuG', 'else']),
-    ).resolves.toBeUndefined();
-
-    expect(concurrentlyCalls()).toMatchInlineSnapshot(`
-      Array [
-        Object {
-          "command": "eslint --debug --ext=js,ts,tsx --report-unused-disable-directives .",
-          "env": "REDACTED",
-          "name": "ESLint  ",
-          "prefixColor": "magenta",
-        },
-        Object {
-          "command": "tsc --extendedDiagnostics --noEmit",
-          "env": "REDACTED",
-          "name": "tsc     ",
-          "prefixColor": "blue",
-        },
-        Object {
-          "command": "prettier --check --loglevel debug .",
-          "env": "REDACTED",
-          "name": "Prettier",
-          "prefixColor": "cyan",
-        },
-        Object {
-          "maxProcesses": "REDACTED",
-          "outputStream": undefined,
-          "prefix": "{name} |",
-        },
-      ]
-    `);
-  });
-});
-
-describe('internalLint', () => {
-  it('passes on skuba itself', () =>
-    expect(internalLint()).resolves.toBeUndefined());
-});
+import './lint';
 
 /**
  * Ensure compatibility between our lint command and new syntax features.